The invention relates to a process and system for improving quality of a heavy and/or extra heavy hydrocarbon, and especially for recovering and improving the quality of hydrocarbons in waste drilling fluids.
Hydrocarbon waste pits are used to store accumulated waste drilling fluids during the process of drilling for the production of oil, as well as during exploitation of a given oil field. During drilling, it is necessary to insert a drill bit and accessories to remove waste sand. In order to facilitate drilling, drilling fluids are used. As the drill bit perforates through the various subterranean formations, the drilling fluids mix with petroleum crude and the resulting mixture of used fluids is disposed of, typically in a pit for intended later treatment.
However, as the accumulation within pits starts to get large, there is no suitable technology for properly treating it. A large amount of crude hydrocarbon is stored within the waste drilling fluids. In some cases, the amount of hydrocarbon present in drilling pits is much greater than the drilling fluid. With time, the fluids in these pits are transferred to large reservoirs from which it is intended to recover at least the hydrocarbon fraction, but this has met with little or no success. Additionally, the waste water and the drilling cuts are not separated for appropriate disposal.
This causes a problem in that many reservoirs are used for accumulating large quantities of waste hydrocarbon products and drilling cuts for years, without any intervention for recovering any product from them. In these waste pits, the amount of hydrocarbons is so large that if recovered, it could be used downstream in a refinery or any other process capable of transforming the recovered hydrocarbon.
Another important issue related to the disposal and accumulation of waste drilling fluids is that pits holding these fluids can contaminate ground water and soil by slow permeation of such fluids through the soil, creating an environmental problem for future generations.
In some instances, such fluids are treated just to the extent of removing water and drilling fluids, while the large amount of hydrocarbon remaining is transferred to another reservoir, typically a much bigger one, which accumulates huge quantities of such hydrocarbons for a very long time, without any treatment whatsoever. The hydrocarbon contained in these reservoirs does not have the quality to be used in any other process. Thus, these large pits or reservoirs are kept indefinitely.
In other instances, waste hydrocarbons contained in such reservoirs are incinerated, which of course wastes the hydrocarbon resource and also leads to environmental issues.
Attempts to recover hydrocarbon are made difficult by the presence of emulsions of water in hydrocarbon which are very difficult to break. Attempts to treat such waste hydrocarbons include a multi-step procedure requiring dilution, demulsification, heating and centrifugation.
Even when this multi-step process is used, the hydrocarbon product obtained has a large quantity of unwanted material that limits or prevents use of the hydrocarbon in downstream refining or other processes.
Clearly, the need exists for a process to recover hydrocarbons from waste hydrocarbon sources such as waste drilling fluid pits and the like.
There is no known technology capable of recovering and improving the quality of waste hydrocarbon products coming from large drilling cut pits, at low cost.
Similar needs are also present in some heavy or extra heavy hydrocarbons produced from a well after production has started. It is known to extract heavy and extra heavy hydrocarbons and treat them through dilution with light or medium hydrocarbons, to produce so-called syncrude. However, such processes are done for transportation purposes, and do not meaningfully improve or upgrade the product.
Extraction of hydrocarbons coming from tar sands or bituminous sands is usually done by using a combination of water, sodium hydroxide and high temperature. This leads to increased costs, and is an environmentally harsh treatment.
Thus, there are further needs for improved methods to produce and upgrade heavy and extra heavy hydrocarbons, and hydrocarbons from tar sands or bituminous sands, at reduced cost and in a more environmentally friendly manner.
De-asphaltation processes are used for improving heavy and extra heavy crude hydrocarbons. Examples of these known processes include U.S. Pat. Nos. 4,017,383; 4,482,453; 4,572,781; 4,747,936; 4,781,819; 5,944,984 and 6,405,799. However, these processes are carried out at severe pressure and temperature which prevent their economic use.
Based upon the foregoing, it is the primary object of the invention to provide a low cost process for recovering and upgrading heavy and extra heavy hydrocarbons from waste drilling fluid pits, reservoirs and the like.
It is a further object of the invention to provide such a process which uses low cost and highly available materials.
It is a further object of the invention to provide a system for carrying out the process which is modular in design and easy to install, use and maintain.
Other objects and advantages of the invention will appear below.